ORCHID

This handsome flower has a great number of species and varieties requiring many different methods of culture which need special study. They are not, however, beyond the capacity of the amateur with hot and cool greenhouses, and for successful rearing special books on the subject should be consulted. Here, some general remarks may be of guidance. Only a few orchids take kindly to sharing a greenhouse with other plants or, rather, other plants cannot thrive as they should under conditions which suit orchids. Consequently it is usual to house them on their own in either a cool or a warm greenhouse according to species and needs. In addition to the ordinary ventilators, one or two should be pierced in the lower structure on the sliding door plan to regulate the volume of incoming air. These ventilators should be placed in such a position that the current passes over the heating pipes and so becomes less frigid. In cold weather, when using these, the top ventilators in the glass sides need not be opened. Those orchids which do well in a cool house require a temperature of 55 degrees F. in winter, 60 degrees F. in summer; those requiring a warmer temperature or an ‘intermediate’ house need a minimum winter temperature of 55 degrees F. and about 70 degrees F. in summer. Hothouse orchids should have not less than 65 degrees F. in winter and 75 degrees F. in summer. It is, however, possible to mix different classes of orchids, given a minimum winter temperature of 55 degrees F., especially if thermostatically controlled electric heating is installed. Polythene lining to the greenhouse will help to keep up the humidity. Variations in temperature should be adjusted gradually.

Greenhouses, whether cool or warm, must have blinds to shade from extremes of light, the cool house requiring shade so long as the sun is on the house. Alternatively, the glass may be coated with a proprietary shading solution. The measure of sunlight depends on the class of orchid but this is an observed rule. In the winter all natural light is needed. The art of ventilation can only be learned by experience and the needs of individual species, but always use the ventilators in the apex with reserve. Their use is to keep the air pure.

Suitable potting soils vary with each class and are best ascertained when buying specimens, but a rich compost in which sphagnum moss is an ingredient is a common basic factor.

New stock should always be given new pots. For repotting this is not so necessary, but each pot must be scrubbed in warm water and sun- or fire-dried before use. The hanging sorts need wire-hooked wooden baskets, preferably of teak, in which rough fibre forms the drainage foundation. For pot drainage the crocks should fill at least a fifth of the pot, and must be washed before being used.

Re-potting work is done when new growth shows rooting at the base, which is usually soon after the main plant has flowered. Give extra shade to re-potted orchids. Always use rainwater.for watering, very slightly warmed during winter, and pour it on carefully to avoid sprinkling the young growth. Only water when needed, but amply. Do not water through the rose. Increase by division when potting. The orchid is happily not prone to disease; judicious ventilation, atmospheric moisture and scrupulous adherence to a correct temperature in the house, are good preventatives.

Slugs and woodlice have to be guarded against. Among the numerous orchids that are relatively easy to growCypripedium insigne Sanderae is primrose-yellow and blooms in winter. Cymbidiums and Oncidiums are also suitable for the cool house. For the intermediate house, Miltonias can be recommended. For the hot house Calanthes, Odontoglossums and Vandas are possibilities. A hardy, open-air genus is the orchis, .